Some new ideas in Leptogenesis and Dark Matter studies

• Rome Samanta (Southampton Univ)

An updated review is presented of the theory of low-energy antikaon and hyperon interactions with nucleons and nuclear systems. Applications include kaonic hydrogen, recent calculations of kaonic deuterium and comparisons with K-p correlation functions from ALICE at LHC. This is followed by a discussion of the possible role played by kaons and hyperons in dense baryonic matter, with special emphasis on constraints provided by the existence of two-solar-mass neutron stars and garvitational wave signals of neutron star mergers.

Global fits to 𝑏→𝑐𝜏𝜈 transitions

• Ana Peñuelas (U. Valencia, IFIC)

We perform a general model-independent analysis of $b \to c \tau \bar{\nu}_\tau $ transitions, including measurements of $\mathcal{R}_D$, $\mathcal{R}_{D^*}$, their $q2$ differential distributions, the recently measured longitudinal $D^*$ polarization $F_L^{D^*}$, and constraints from the $B_c \to \tau \bar{\nu}_\tau$ lifetime, each of which has significant impact on the fit. A global fit to a general set of Wilson coefficients of an effective low-energy Hamiltonian is presented, the solutions of which are interpreted in terms of hypothetical new-physics mediators. From the obtained results we predict selected $b \to c\tau\bar\nu_\tau$ observables, such as the baryonic transition $\Lambda_b \to \Lambda_c \tau \bar{\nu}_\tau$, the ratio $\mathcal{R}_{J/\psi}$, the forward-backward asymmetries ${\cal A}_\text{FB}^{D^{(*)}}$, the $\tau$ polarization asymmetries $\mathcal{P}_\tau^{D^{(*)}}$, and the longitudinal $D^*$ polarization fraction $F_L^{D^*}$. The latter shows presently a slight tension with any new-physics model, such that an improved measurement could have an important impact.

Asymptotic safety with N_F flavors

• Enrico Maria Sessolo (NCBJ Warsaw)

I will discuss recent developments in calculating beta functions of a generic gauge-Yukawa theory augmented by N_F flavors of heavy vector-like fermions. In the limit of large N_F it is possible to reorder the perturbative expansion with 1/N_F as ordering parameter, and then resum the tower of loop diagrams with ever-increasing number of vacuum-polarization bubbles at the leading order in 1/N_F. The resummed expression is finite and presents a pole at a non-perturbatively large value of the coupling. When applied to the gauge beta function, this mechanism can allow one to generate an interacting UV fixed-point and, for gauge symmetry groups not containing an abelian component, give rise to an asymptotically safe theory. Some possible applications of these constructions might pertain to flavor model building.